Spectrally encoded endoscope (“SEE”) is an endoscope technology which uses a broadband light source, a rotating grating and a spectroscopic detector to encode spatial information on a sample. When illuminating light to the sample, the light is spectrally dispersed along one illumination line, such that the dispersed light illuminates a specific position of the illumination line with a specific wavelength. When the reflected light from the sample is detected with the spectrometer, the intensity distribution is analyzed as the reflectance along the line. By rotating or swinging the grating back and forth to scan the illumination line, a two-dimensional image of the sample is obtained. SEE techniques have been described in, e.g., U.S. Patent Publication Nos. 2007/0233396 and 2008/0013960, which are herein incorporated by reference in their entireties.
Doctors will often use color information as cues to diagnosis. However, by using wavelength information to encode spatial location, SEE images cannot provide color images as simply, and important color information may be lost. Color SEE can be realized by illuminating the grating with several different incidence angles, each with light of a respective wavelength band of color, so that light with color of red, green and blue each spectrally disperses on to the sample on one line and overlapping each other. Spectrally encoded endoscope had one grating at the tip to disperse light in one dimension and in one plane. It required three fibers with a different wavelength band. This is described in U.S. Patent Publication No. 2011/0237892, which is herein incorporated by reference in its entirety, and by D. Kang et al., Opt. Exp. Vol. 17, No. 17, 15239 (2009).
However, the use of multiple fibers potentially enlarges the diameter of the probe and it complicates the system at the proximal end when a rotary junction is used since, for example, the probe needs to be disconnected for an exchange of the probe and each fiber requires a separate connector at the proximal end.
Further, existing spectrally encoded endoscopes irradiate the sample with one spectral bandwidth of light with approximately the same incident angle. This limited the dispersion of the light and limited the field of view of the spectrally encoded endoscope. However, an increased field of view is important for some endoscopic applications, and when increasing the field of view where the diffraction overlaps in one plane (or one line on the sample) there is an increase in crosstalk when collecting light and recreating the image from spectrally encoded light.
Accordingly, there may be a need to address and/or overcome at least some of the issues described herein above.